The present disclosure relates to a purification method of a polymerization solvent used in and recovered from the preparation of a polyolefin resin, which can effectively remove impurities, in particular polyolefin wax, from the polymerization solvent to obtain a purified polymerization solvent with high purity, and can improve energy efficiency.

The present disclosure relates to a purification method of a polymerization solvent used in and recovered from the preparation of a polyolefin resin, which can effectively remove impurities, in particular polyolefin wax, from the polymerization solvent to obtain a purified polymerization solvent with high purity, and can improve energy efficiency.

A method for producing particles of a fluorinated polymer (A) which has either one or both of structural units (u1) derived from tetrafluoroethylene and structural units (u2) having no sulfonic acid type functional group and having a cyclic structure and fluorine atoms, and which has structural units (u3) having a sulfonic acid type functional group, wherein the proportion of the structural units (u1) is from 0 to 82 mol % in all structural units in the fluorinated polymer (A), the method including: (i) preparing solution or dispersion of the fluorinated polymer (A) having the fluorinated polymer (A) dissolved or dispersed in a solvent (B); and (ii) mixing the solution or dispersion of the fluorinated polymer (A) and a solvent (C) to aggregate the fluorinated polymer (A) to form particles of the fluorinated polymer (A).

A method for producing particles of a fluorinated polymer (A) which has either one or both of structural units (u1) derived from tetrafluoroethylene and structural units (u2) having no sulfonic acid type functional group and having a cyclic structure and fluorine atoms, and which has structural units (u3) having a sulfonic acid type functional group, wherein the proportion of the structural units (u1) is from 0 to 82 mol % in all structural units in the fluorinated polymer (A), the method including: (i) preparing solution or dispersion of the fluorinated polymer (A) having the fluorinated polymer (A) dissolved or dispersed in a solvent (B); and (ii) mixing the solution or dispersion of the fluorinated polymer (A) and a solvent (C) to aggregate the fluorinated polymer (A) to form particles of the fluorinated polymer (A).

Provided are processes for upconcentrating fluoropolymer dispersions. Also provided are upconcentrated dispersions and substrates coated with such dispersions.

Provided are processes for upconcentrating fluoropolymer dispersions. Also provided are upconcentrated dispersions and substrates coated with such dispersions.

Provided are processes for upconcentrating fluoropolymer dispersions. Also provided are upconcentrated dispersions and substrates coated with such dispersions.

The present invention provides an aqueous dispersion of a low-molecular-weight polytetrafluoroethylene (PTFE), which contains an easily removable surfactant, and has a good dispersion stability. Specifically, the present invention provides an aqueous dispersion of a low-molecular-weight PTFE comprising tetrafluoroethylene (TFE) units, or TFE units and modifying monomer units which are copolymerizable with the TFE units, wherein the aqueous dispersion contains from 70 to 9,000 ppm, based on the aqueous dispersion, of a fluorine-containing compound of the formula (1) below:
X(CF.sub.2).sub.mY(1)
where X is H or F; m is an integer from 3 to 5; and Y is SO.sub.3M, SO.sub.4M, SO.sub.3R, SO.sub.4R, COOM, PO.sub.3M.sub.2 or PO.sub.4M.sub.2, M being H, NH.sub.4 or an alkali metal, and R being an alkyl group having 1 to 12 carbons, and the low-molecular-weight PTFE has an average primary particle size of from 100 to 350 nm.

The present invention provides an aqueous dispersion of a low-molecular-weight polytetrafluoroethylene (PTFE), which contains an easily removable surfactant, and has a good dispersion stability. Specifically, the present invention provides an aqueous dispersion of a low-molecular-weight PTFE comprising tetrafluoroethylene (TFE) units, or TFE units and modifying monomer units which are copolymerizable with the TFE units, wherein the aqueous dispersion contains from 70 to 9,000 ppm, based on the aqueous dispersion, of a fluorine-containing compound of the formula (1) below:
X(CF.sub.2).sub.mY(1)
where X is H or F; m is an integer from 3 to 5; and Y is SO.sub.3M, SO.sub.4M, SO.sub.3R, SO.sub.4R, COOM, PO.sub.3M.sub.2 or PO.sub.4M.sub.2, M being H, NH.sub.4 or an alkali metal, and R being an alkyl group having 1 to 12 carbons, and the low-molecular-weight PTFE has an average primary particle size of from 100 to 350 nm.

The present invention provides an aqueous dispersion of a low-molecular-weight polytetrafluoroethylene (PTFE), which contains an easily removable surfactant, and has a good dispersion stability. Specifically, the present invention provides an aqueous dispersion of a low-molecular-weight PTFE comprising tetrafluoroethylene (TFE) units, or TFE units and modifying monomer units which are copolymerizable with the TFE units, wherein the aqueous dispersion contains from 70 to 9,000 ppm, based on the aqueous dispersion, of a fluorine-containing compound of the formula (1) below:
X(CF.sub.2).sub.mY(1)
where X is H or F; m is an integer from 3 to 5; and Y is SO.sub.3M, SO.sub.4M, SO.sub.3R, SO.sub.4R, COOM, PO.sub.3M.sub.2 or PO.sub.4M.sub.2, M being H, NH.sub.4 or an alkali metal, and R being an alkyl group having 1 to 12 carbons, and the low-molecular-weight PTFE has an average primary particle size of from 100 to 350 nm.